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  1. MariaDB Server
  2. MDEV-26699

Row counter does not work consistently for Columnstore tables

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    Description

      Below are some examples how the row counter can be right or wrong for Columnstore tables, and some loosely related MCOL bugs are linked. I don't expect it to be fixable on the server side or to be fixed on the Columnstore side, and I doubt we can spell any meaningful rules for the end users for when ERROR_INDEX works for Columnstore and when doesn't, so I lean towards passing it over straight to documentation to issue a blank statement that it cannot be relied upon when Columnstore is involved.

      This works

      10.7 8dd4794c4e1

      		 
      MariaDB [db]> create table t (a tinyint) engine=Columnstore;
      		 
      Query OK, 0 rows affected (0.661 sec)
      		 
       
      		 
      MariaDB [db]> insert into t values (1),(200);
      		 
      ERROR 1264 (22003): Out of range value for column 'a' at row 2
      		 
       
      		 
      MariaDB [db]> set @n = null; get diagnostics condition 1 @n = error_index; select @n;
      		 
      Query OK, 0 rows affected (0.001 sec)
      		 
       
      		 
      Query OK, 0 rows affected (0.000 sec)
      		 
       
      		 
      +------+
      		 
      | @n   |
      		 
      +------+
      		 
      |    2 |
      		 
      +------+
      		 
      1 row in set (0.000 sec)

      This doesn't:

      MariaDB [db]> create table t (a tinyint) engine=Columnstore;
      		 
      Query OK, 0 rows affected (0.701 sec)
      		 
       
      		 
      MariaDB [db]> insert into t values (1),(100);
      		 
      Query OK, 2 rows affected (0.530 sec)
      		 
      Records: 2  Duplicates: 0  Warnings: 0
      		 
       
      		 
      MariaDB [db]> update t set a = a*2;
      		 
      ERROR 1264 (22003): CAL0002: IDB-2025: Data truncated for column 'a' 
      MariaDB [db]> show warnings;
      		 
      +-------+------+---------------------------------------------------------------------+
      		 
      | Level | Code | Message                                                             |
      		 
      +-------+------+---------------------------------------------------------------------+
      		 
      | Error | 1264 | CAL0002: IDB-2025: Data truncated for column 'a'                    |
      		 
      | Error | 1030 | Got error 1815 "Unknown error 1815" from storage engine ColumnStore |
      		 
      +-------+------+---------------------------------------------------------------------+
      		 
      2 rows in set (0.000 sec)
      		 
       
      		 
      MariaDB [db]> set @n1 = null, @n2 = null; get diagnostics condition 1 @n1 = error_index; get diagnostics condition 2 @n2 = error_index; select @n1, @n2;
      		 
       
      		 
      +------+------+
      		 
      | @n1  | @n2  |
      		 
      +------+------+
      		 
      |    1 |    1 |
      		 
      +------+------+
      		 
      1 row in set (0.000 sec)

      This also doesn't:

      MariaDB [db]> insert into t select a * 2 from t;
      		 
      ERROR 1264 (22003): Out of range value for column 'a' at row 1
      		 
      MariaDB [db]> show warnings;
      		 
      +-------+------+--------------------------------------------+
      		 
      | Level | Code | Message                                    |
      		 
      +-------+------+--------------------------------------------+
      		 
      | Error | 1264 | Out of range value for column 'a' at row 1 |
      		 
      +-------+------+--------------------------------------------+
      		 
      1 row in set (0.001 sec)
      		 
       
      		 
      MariaDB [db]> set @n = null; get diagnostics condition 1 @n = error_index; select @n;
      		 
      Query OK, 0 rows affected (0.000 sec)
      		 
       
      		 
      Query OK, 0 rows affected (0.000 sec)
      		 
       
      		 
      +------+
      		 
      | @n   |
      		 
      +------+
      		 
      |    1 |
      		 
      +------+
      		 
      1 row in set (0.000 sec)

      It can also fail in a different way (MCOL-4879), which doesn't do any good to the counter either:

      MariaDB [db]> insert into t select a * 2 from t;
      		 
      ERROR 1815 (HY000): Internal error: Unknown error
      		 
      MariaDB [db]> set @n = null; get diagnostics condition 1 @n = error_index; select @n;
      		 
      Query OK, 0 rows affected (0.000 sec)
      		 
       
      		 
      Query OK, 0 rows affected (0.000 sec)
      		 
       
      		 
      +------+
      		 
      | @n   |
      		 
      +------+
      		 
      |    1 |
      		 
      +------+
      		 
      1 row in set (0.000 sec)

      I've set affected version to 10.5+ as I don't suppose the counter works any better than in 10.7, but I only tried 10.7. I don't think there is any place to document it for 10.5-10.6, but for the new diagnostics addition in 10.7 the mention of it may be suitable.

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          is caused by

          Task - A task that needs to be done. MDEV-10075 Provide index of error causing error in array INSERT

          • Blocker - Blocks development and/or testing work, production could not run.
          • Closed
          relates to

          Bug - A problem which impairs or prevents the functions of the product. MCOL-4877 Too long values are silently truncated without errors or warnings upon UPDATE

          • Major - Major loss of function.
          • Open

          Bug - A problem which impairs or prevents the functions of the product. MCOL-4879 Error code miscommunication between Columnstore and server

          • Trivial - Cosmetic problem like misspelt words or misaligned text.
          • Open

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              rucha174 Rucha Deodhar
              elenst Elena Stepanova
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                Updated:

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